#include <assert.h>
#include <stdio.h>

#define MAXN 1000

typedef int DataType;
int n;//num in the array
DataType v[MAXN];

int sorted()
{
  int i;
  for(i=0;i<n-1;++i)
    if(v[i]>v[i+1])
      return 0;//unsorted
  return 1;//sorted
}

int lower_bound(DataType key)
/*precondition: v is sorted in nondecreasing order v[i]<=v[i+1]
  postcondition:
  result = -1    =>   all the elements in v are less than key
  0<=result<n    =>   v[result] is the first element greater or equal to key
*/
{
  int low,mid,high;
  int size,oldsize;
  assert(sorted());
  low = 0;
  high = n-1;
  size = n+1;
  if(low > high) //empty array
    return -1;
  if(key > v[high]) //all the element in the array is less than key
    return -1;
  //loop invariant: the first elemen >= key is in [low,high]
  while(low < high){
    oldsize = size;
    size = high-low+1;
    assert(size<oldsize);

    mid = (low+high)/2;
    if(v[mid]<key)
      low = mid+1;
    else {
      assert(0<=mid && mid<n && v[mid]>=key);
      high = mid;
    }
  }
  assert( low == high );
  return low;
}

int main()
{
  int i;
  DataType key;
  while(scanf("%d %d",&n,&key) !=EOF) {
    for(i = 0; i<n; ++i)
      v[i] = i*10;
    printf(" %d\n",lower_bound(key) );
  }
  return 0;
}
